I'm stumped...my 420SEL has has an intermittent stumble,rough running problem ever since I powerwashed under the hood about 30 days ago. It would initially not run at all, then ran OK sometimes, then would stumble and stall under load, but there was no rhyme or reason to it. Today I went for a spin...ran fine for 15 miles or so, a mix of Interstate and surfaace streets. In the past, it seemed to be worst trying to accelerate from a stop, that was when it was most prone to stalling and running funny. It was fine. I drove it several hours later, and it stumbled several times...the new symptom is this: I heard a clicking from the dash each time it stumbled...the recirc button on the dash would light up and click in rhythm with the engine stumble. I pushed the switch "off" and it didn't do it any more, pushed it "on" and it stumbled once, but never again when I manually switched the recirc on and off. Any thoughts and suggestions?

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2002 Ford ZX2
2 x 2013 Honda Civics